Hello,
The problem I have faced after Jira upgrade is that, in priority schemes, there is not a Default Priority Scheme. Therefore, I cannot create new project also priorty field is empty in issue creation screen. Interesting part is that, I have also upgraded same Jira instance with same DB in DEV environment but there was not any problem about priority schemes I tried to insert default priorty scheme in database but did not work.
Any kind of advice will be helpful. Thanks.